Carla Matos

Ethnopharmacological notes about ancient uses of medicinal plants in Trás-os-Montes (northern of Portugal)

AIM OF THE STUDY In order to preserve the ancestral knowledge, an ethnopharmacological study has been carried out in two councils belonging to Trás-os-Montes region a small area located in the northern of Portugal. In that area, medicinal plants, most of the species wild, are still in use among farmers, shepherds and other people who live far from villages and built-up areas. MATERIALS AND METHODS Among the 46 people that were interviewed (mean age of 66 years old), 88 species belonging to 42 families of vascular plants were identified for treatment of various human ailments. An ethnopharmacological report is made consisting of species names, vernacular names, popular uses of the plants and their pharmacological properties. RESULTS AND CONCLUSION The most dominant family is Lamiaceae (18%) and the most frequently part of the plant used for the treatment of diseases are leaves (37.9%). The largest number of taxa is used to treat gastrointestinal disorders (73.9%).

Nanoencapsulation of bovine lactoferrin for food and biopharmaceutical applications

Lactoferrin has for long captured the interest of many researchers as a natural compound with a wide variety of uses. Lactoferrin is a monomeric, iron-binding 80 kDa glycoprotein, and appears to be the subfraction of whey with the best documented antiviral, antimicrobial, anticancer and immune modulating/enhancing effects. It belongs to the family of transferrin proteins, and serves to control iron levels in body fluids by sequestering and solubilizing ferric iron. In the present research effort, production of lactoferrin derivatives (starting from a purified commercial extract), encompassing full stabilization of its three-dimensional structure, has been attempted via nanoencapsulation within lipid nanovesicles, integrating a multiple water-in-oil-in-water emulsion. Long-term storage of the multiple nanoemulsions produced did not lead to leaching of protein, thus proving the effectiveness of the encapsulation procedure. Furthermore, lactoferrin nanovesicle derivatives prepared under optimal conditions were successfully employed at lab-scale antimicrobial trials.

Evaluation of solubility and partition properties of ampicillin-based ionic liquids

In order to overcome the problems associated with low water solubility, and consequently low bioavailability of active pharmaceutical ingredients (APIs), herein we explore a modular ionic liquid synthetic strategy for improved APIs. Ionic liquids containing L-ampicillin as active pharmaceutical ingredient anion were prepared using the methodology developed in our previous work, using organic cations selected from substituted ammonium, phosphonium, pyridinium and methylimidazolium salts, with the intent of enhancing the solubility and bioavailability of L-ampicillin forms. In order to evaluate important properties of the synthesized API-ILs, the water solubility at 25 °C and 37 °C (body temperature) as well as octanol-water partition coefficients (Kows) and HDPC micelles partition at 25 °C were measured. Critical micelle concentrations (CMCs) in water at 25 °C and 37 °C of the pharmaceutical ionic liquids bearing cations with surfactant properties were also determined from ionic conductivity measurements.

Interaction of Antiinflammatory Drugs with EPC Liposomes: Calorimetric Study in a Broad Concentration Range

Isothermal titration calorimetry was used to characterize and quantify the partition of indomethacin and acemetacin between the bulk aqueous phase and the membrane of egg phosphatidylcholine vesicles. Significant electrostatic effects were observed due to binding of the charged drugs to the membrane, which implied the use of the Gouy-Chapman theory to calculate the interfacial concentrations. The binding/partition phenomenon was quantified in terms of the partition coefficient (K(p)), and/or the equilibrium constant (K(b)). Mathematical expressions were developed, either to encompass the electrostatic effects in the partition model, or to numerically relate partition coefficients and binding constants. Calorimetric titrations conducted under a lipid/drug ratio >100:1 lead to a constant heat release and were used to directly calculate the enthalpy of the process, DeltaH, and indirectly, DeltaG and DeltaS. As the lipid/drug ratio decreased, the constancy of reaction enthalpy was tested in the fitting process. Under low lipid/drug ratio conditions simple partition was no longer valid and the interaction phenomenon was interpreted in terms of binding isotherms. A mathematical expression was deduced for quantification of the binding constants and the number of lipid molecules associated with one drug molecule. The broad range of concentrations used stressed the biphasic nature of the interaction under study. As the lipid/drug ratio was varied, the results showed that the interaction of both drugs does not present a unique behavior in all studied regimes: the extent of the interaction, as well as the binding stoichiometry, is affected by the lipid/drug ratio. The change in these parameters reflects the biphasic behavior of the interaction-possibly the consequence of a modification of the membranes physical properties as it becomes saturated with the drug.

A fast and reliable spectroscopic method for the determination of membrane--water partition coefficients of organic compounds.

Partition coefficients (Kp) between egg yolk phosphatidylcholine multilamellar vesicles and water were determined for two nonsteroidal anti-inflammatory drugs (indomethacin and acemetacin) using two independent methodologies: derivative spectrophotometry and variation of the experimental acidity constant in the presence of increasing vesicle concentration. Second-derivative spectrophotometry allowed for total elimination of background signal effects arising from lipid vesicles, without the need for separation techniques that may disturb equilibrium states. By using a model based on a simple partition, the values of KpT can be obtained directly; furthermore, by performing determinations at two different pH values it is possible to calculate partition coefficients for the neutral and negatively charged forms of the drugs (KpAH and KpA). In the other methodology, values of apparent acidity constants (Kapp) were determined by spectrophotometry at different pH values and different lipid concentrations, and an increase in Kapp with decreasing lipid concentration was observed for both drugs, and from this dependence it was possible to calculate KpAH and KpA- for each drug. These values were used as a check for those obtained by derivative spectroscopy, which has proven to be a reliable and more expeditious method to obtain KpAH and KpA-.

Interaction of drugs with hexadecylphosphocholine micelles. Derivative spectroscopy, acid–base and solubility studies

Abstract The zwitterionic detergent hexadecylphosphocholine (HDPC) is structurally similar to the phospholipids present in natural membranes, and the study of the drug/HDPC micelle interaction can be of interest in drug–activity relationship studies. The effect of these micelles on the spectroscopic, acid–base and solubility properties of two non-steroidal anti-inflammatory drugs, indomethacin and acemetacin , was studied at different pH values. From the dependence of these physical properties on HDPC concentration, by fitting mathematical models based on the simple partition of the drugs between two pseudo-phases to the data, it was possible to calculate the drug/micelle binding constants, which can be related to the water/micelle partition coefficients. It was found that the three techniques yield similar results and that by performing the determinations at any two pH values, it is possible to calculate the binding constants for the neutral and negative forms of the drugs ( K b AH and K b A − ). Furthermore, the knowledge of K b AH and K b A − allows the prediction of K b T for any given pH, avoiding experimental pH conditions that can be troublesome, related with drug stability or solubility problems.

Location and partition coefficients of anti-inflammatory drugs in EPC liposomes. A fluorescence quenching study using n-(9-anthroyloxy)-stearic probes

Steady-state fluorescence quenching of a series of n-(9-anthroyloxy) stearic acids (n-AS, n=2, 6, 9 and 12) was used to investigate the location of two anti-inflammatory drugs, namely indomethacin and acemetacin, in multilamellar and unilamellar egg phosphatidylcholine liposomes (EPC) at two pH values (7.4 and 5.0). The quenching properties were also used in determining quantitatively the partition coefficient of both drugs in multilamellar and unilamellar EPC vesicles, at pH 7.4 using a 12-AS probe. All n-AS probes were quenched by both drugs and the relative quenching efficiencies are in the order 2-AS<6-AS<9-AS<12-AS. At pH 5.0, the apparent Stern–Volmer constant values, kqapp, were always higher than those obtained at pH 7.4. The partition coefficients determined at pH 7.4 lead to higher values for acemetacin than for indomethacin, especially for multilamellar liposomes (MLVs) and are identical, within experimental error, to those obtained by other methods. The observation that the kqapp values increase with the depth of the probe (larger n) for both drugs at pH 7.4 suggests that the anti-inflammatory drugs can reach the inner part of the bilayer, probably with the negative carboxyl group anchored near the choline of the phospholipid headgroup, and with the rest of the molecule buried deeply in the membrane and aligned with the phospholipid aliphatic tails. Quenching of 12-AS is larger in MLVs than in LUVs, which can be related to the different packing of the lipids in these structures, and also to the different drug penetrations in the bilayer.

Liposomes as a model for the biological membrane: studies on daunorubicin bilayer interaction.

In this study the interaction of the antitumoral drug daunorubicin with egg phosphatidylcholine (EPC) liposomes, used as a cell membrane model, was quantified by determination of the partition coefficient (Kp). The liposome/aqueous-phase Kp of daunorubicin was determined by derivative spectrophotometry and measurement of the zeta-potential. Mathematical models were used to fit the experimental data, enabling determination of Kp. In the partition of daunorubicin within the membrane both superficial electrostatic and inner hydrophobic interactions seem to be involved. The results are affected by the two types of interaction since spectrophotometry measures mainly hydrophobic interactions, while zeta-potential is affected by both interpenetration of amphiphilic charged molecules in the bilayer and superficial electrostatic interaction. Moreover, the degree of the partition of daunorubicin with the membrane changes with the drug concentration, due mainly to saturation factors. Derivative spectrophotometry and zeta-potential variation results, together with the broad range of concentrations studied, revealed the different types of interactions involved. The mathematical formalism applied also allowed quantification of the number of lipid molecules associated with one drug molecule.

Nanocarrier possibilities for functional targeting of bioactive peptides and proteins : state-of-the-art

This review attempts to provide an updated compilation of studies reported in the literature pertaining to production of nanocarriers encasing peptides and/or proteins, in a way that helps the reader direct a bibliographic search and develop an integrated perspective of the subject. Highlights are given to bioactive proteins and peptides, with a special focus on those from dairy sources (including physicochemical characteristics and properties, and biopharmaceutical application possibilities of e.g. lactoferrin and glycomacropeptide), as well as to nanocarrier functional targeting. Features associated with micro- and (multiple) nanoemulsions, micellar systems, liposomes and solid lipid nanoparticles, together with biopharmaceutical considerations, are presented in the text in a systematic fashion.

Synthesis, Characterization, and Liposome Partition of a Novel Tetracycline Derivative Using the Ionic Liquids Framework

Recently, efforts have been put on the development of new drug formulations using ionic liquid framework. In this work, two different species of abroad-spectrum polyketide antibiotic, tetracycline, are studied in terms of some important properties for antibiotics such as solubility in water and hydrophilic-hydrophobic balance. Tetracycline was used as cation, whereas docusate, a biocompatible anion, which enables the tailoring of the hydrophilicity of salts, was chosen as the anion. The developed innovative ion pair, tetracycline docusate, was characterized in terms of its thermal stability, water solubility, octanol-water, and liposome-water partition coefficients, using UV-vis spectrophotometry because of the absorbance of tetracycline around 270 nm. Egg yolk phosphatidylcholine liposomes were used as cell membrane models, and the interactions of both tetracycline hydrochloride and tetracycline docusate with the liposomes were quantified by determination of the partition coefficient using derivative spectrophotometry. A theoretical model based on simple partition drugs between two different media was used to determine the partition coefficient in liposomes.